| abstract |
(57) Abstract: A cis-1,4-polybutadiene rubber excellent in abrasion resistance, impact resilience, exothermicity, strength characteristics and workability, a method for producing the same, and a rubber composition containing the rubber are provided. . SOLUTION: The weight average molecular weight (Mw) measured by gel permeation chromatography having a cis 1,4-bond of 60% or more is 100,000 to 1,000,000, and the weight average molecular weight (Mw) and the number average molecular weight (Mn). ) Ratio (Mw / Mn) Is 2.5 or less, and the ratio (Rz / Mz) of the Z average mean square radius of gyration (Rz) and the Z average absolute molecular weight (Mz) is 50 ×. A cis-1,4-polybutadiene rubber having a viscosity of 10 −12 m · mol · kg −1 or more is used. |